Williams back to her best against Sharapova

Serena Williams sent out an ominous message to the women's game as she stormed past Maria Sharapova, booking her place in the semi-finals of the Bank of the West Classic for the loss of just four games.

The American, down to 169 in the world following a year of injury and health problems, was close to her powerful best as she raced to a 6-1 6-3 win over the Wimbledon finalist and second seed in 69 minutes.